Abstract:

Fly ash was used as a raw material，potassium hydroxide solution was used as an alkali activator，and the mixture was uniform according to the optimized ratio[n（K₂O）/n（Al₂O₃）=1.5，n（H₂O）/n（Na₂O）=18].The fly ash-based geoploymer microspheres were prepared by suspension solidification method，and it was used to adsorb Cu²⁺ from wastewater containing copper.The microspheres were characterized by X-ray diffraction（XRD），specific surface area and aperture analyzer，BT-99 water quality analyzer.The effects of time，dosage，temperature，pH value，concentration and other factors on the adsorption of Cu²⁺ on the microspheres were explored.The results showed that the fly ash-based geoploymer microspheres had larger pore size，specific surface area and better adsorption effect than fly ash.Under the optimal conditions（dosage of microspheres was 0.20 g，pH of solution was 5，initial mass concentration of Cu²⁺ was 100 mg/L，volume of solution was 100 mL，adsorption temperature was 40 ℃，and adsorption time was 24 h），the adsorption capacity of Cu²⁺ by microspheres was 45.62 mg/g，and the removal rate was 91.46%.The adsorption process was followed the pseudo-second-order kinetic equation.

Key words: fly ash, geoploymer, microspheres, adsorption, Cu²⁺